MHD boundary layer transport of an ethylene-glycol-based Maxwell ternary nanofluid past an exponentially stretching sheet with variable thermal conductivity, nonlinear convection, Arrhenius activation energy and non-uniform heat generation

The enhancement of coupled heat and mass transfer in rheologically complex fluids is a critical challenge in advanced thermal engineering, particularly for systems requiring efficient heat dissipation, controlled rheology, and magnetic responsiveness. This study presents a comprehensive multiphysics analysis of steady, two-dimensional MHD boundary-layer flow of a Maxwell-type ternary hybrid nanofluid over an exponentially stretching impermeable sheet with convective thermal boundary conditions. Ethylene glycol is selected as the base fluid due to its favorable thermal and chemical properties, while copper (Cu), silicon dioxide (SiO 2 ), and magnetite (Fe 3 O 4 ) nanoparticles are incorporated to synergistically enhance thermal conductivity, stability, and magnetic sensitivity. The model incorporates key physical effects, including variable viscosity, temperature- and concentration-dependent electrical conductivity, nonlinear thermal buoyancy, Arrhenius activation energy, non-uniform heat generation, thermal radiation, Brownian motion, thermophoresis, and velocity slip. Using similarity transformations, the governing nonlinear partial differential equations are reduced to ordinary differential equations and solved numerically via the MATLAB bvp4c solver with quasi-linearization. Validation against existing results confirms the accuracy of the computational approach. Parametric analysis indicates that increasing Deborah and Hartmann numbers suppresses fluid velocity, while higher activation energy enhances species concentration. Buoyancy effects promote flow acceleration. Notably, at a matched total volume fraction the Cu–SiO 2 –Fe 3 O 4 /EG ternary nanofluid raises the wall heat-transfer rate by approximately 14–18 % and the mass-transfer rate by approximately 9–12 % relative to the mono nanofluid, thereby outperforming the binary hybrid; the magnitude of this enhancement is shown to depend on the magnetic, viscoelastic and volume-fraction parameters rather than being uniform. These findings provide valuable insights for the design of high-performance thermal systems, including solar collectors, polymer processing, biomedical magnetic transport, and advanced cooling technologies.